Monolithic piezoelectric filter having mass loaded electrodes for resonation regions acoustically coupled together

ABSTRACT

ENERGY IS TRANSMITTED OVER A DESIRED BAND BY APPLYING IT TO A PAIR OF ELECTRODES MOUNTED ON A CRYSTAL BODY AND REMOVING IT FROM ANOTHER PAIR OF ELECTRODES MOUNTED ON THE CRYSTAL BODY. THE ELECTRODES HAVE SUFFICIENT MASSES TO CONCENTRATE THICKNESS SHEAR VIBRATIONS IN THE AREAS BETWEEN THE ELECTRODES. THE ELECTRODES ARE SPACED SUFFICIENTLY FAR FROM THE EDGES OF THE BODY SO AS TO SUBSTANTIALLY ELIMINATE THE EFFECTS OF THE EDGES. THE PAIRS OF ELECTRODES ARE SPACED SO AS TO COUPLE THE RESONATORS FORMED BY THE ELECTRODES AND THE BODY, BUT TO LIMIT THE COUPLING BELOW A GIVEN VALUE.



